#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-11;
const ll mod=1e9+7;
const int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};

double A,B;

double f(double t){
	double x1=t,x2=A-t;
	double y1=min(t/3,B),y2=B-y1;
	return min(x1/3,y1)*4000+min(x2/2,y2/5)*14000;
}

int main(){
	cin>>A>>B;
	double l=0,r=A;
	for(int i=0;i<100;i++){
		double d=(r-l)/3,m=l+d,M=r-d;
		if(f(m)<f(M)) l=m;
		else r=M;
	}
	cout<<syosu(9)<<f(l)<<endl;
}